(A) Field of the Invention
The present invention is related to data writing and reading methods for flash memories and circuitry thereof, more specifically, to methods and their implementation circuitry so that data can be written to or read from flash memories in the same time period.
(B) Description of Related Art
These days, the reading speed of a related flash memory product is becoming more rapid. However, the writing speed cannot keep up with the reading speed, so usually the product cannot perform optimally. Because the manner of writing and the related implementation for writing speed enhancement are not standardized yet, employing current standard flash memories is the most feasible way to increase the writing speed.
The methods for enhancing the writing speed of a flash memory or flash memories can be attained by the following methods. First, employing a temporary-save manner, by which data is temporarily saved in a buffer, and the data is not written into a flash memory until the previous data is completely written into the flash memory. The implementation circuitry of the temporary-save manner is shown in FIG. 1(a), the data bus 102 and the data writing signal line 103 of a data recording circuitry 10 are both connected to a flash memory 101. A writing signal WR is inputted into the flash memory 101 to indicate data Da to be written into the flash memory 101 in order. The implementation of such a temporary-save manner needs only one flash memory, but the writing efficiency is not good enough. The second method is by a circulation writing manner; the exemplified implementation circuitry shown in FIG. 1(b). The flash memories 104, 105 of a data recording circuitry 12 are connected with a data bus 106 and a data writing signal line 107 in parallel. Likewise, data also waits to be written while the previous data is written into the flash memories 104, 105. Nevertheless, the two flash memories 104, 105 can be controlled to respectively write data at different timings for improvement of efficiency.
To date, the access speed and programming speed of the flash memories of an USB disk using USB 1.1 are respectively around 20 Mbps and 1 Mbps, but the data transmission speed of the USB is approximately within 1 Mbps to 1.5 Mbps. Therefore, the data transmission speed usually becomes a speed bottleneck of the USB disk. As to a USB 2.0, the data transmission speed ramps up to 60 Mbps, and thus the access speed and programming speed contrarily become a bottleneck to an USB 2.0 disk. By applying the known manners of the temporary-save or the circulation, the speed of the flash memories can be approximately increased by 30%, i.e., the access speed and programming speed of the flash memories respectively increase to 28 Mbps and 13 Mbps.
Although the above-mentioned methods can improve the data writing efficiency of flash memories, which are still limited to the applications of the electronic devices demanding more high data transmission speed, there is still large room for improvement.